The IEEE (The Institute of Electrical and Electronics Engineers) 1394 standards define the physical and electrical standards of connectors designed for use in various apparatuses to connect the apparatuses to one another. Once an apparatus that has an interface complying with the IEEE1394 standards is physically connected to another apparatus having such an interface, it can achieve hot plug and play and the like, accomplishing high-speed transfer of digital data and automatic setting of connection between the apparatuses. This is why the IEEE1394 standards have been adopted as common serial-interface standards in the industries.
STBs (Set Top Boxes), television receivers, printer apparatuses are known, each having an interface that complies with the above-mentioned IEEE1394 standards.
A method of transmitting Iso packets complying with the IEEE1394 standards, each containing luminance signals and color-difference signals, is disclosed in Jpn. Pat. Appln. Laid-Open Publication No. 10-126426. A printer apparatus complying with the IEEE1394 standards is disclosed in Jpn. Pat. Appln. Laid-Open Publication No. 10-285246.
However, neither a television receivers nor an STB has been connected to a printer apparatus by interfaces complying with the IEEE1394 standards so that the printer apparatus may print the image being displayed by the television receiver.
Hitherto, to print the image displayed by a television receiver by means of a printer apparatus, an interface capable of receiving NTSC (National Television System Committee) signals, i.e., analog signals, from the television receiver or an STB is incorporated in the printer apparatus, and the analog signals are transferred to the printer apparatus, which prints the image being displayed by the television receiver. The analog signals transferred to the printer apparatus have generated by converting digital signals in the television receiver or the STB. The analog signals, thus generated, are deteriorated in quality, disabling the printer apparatus to print fine characters and the like.
To enable the printer apparatus to print the image that the television receiver displays, many printing parameters are set in the television receiver or the STB in most cases. The process-burden on the television receiver or the STB inevitably grows.
The applicant proposed the techniques described in Japanese Patent Application No. 11-191026, Japanese Patent Application No. 11-233252, Japanese Patent Application No. 11-248067 and Japanese Patent Application No. 11-345470, based on which priority is claimed to the present application, to IEEE1394 Trade Association, for the purpose of standardization. IEEE1394 Trade Association disclosed these techniques in the form of the following drafts:                AV/C Printer Subunit Specification Version 1.0 Draft 0.97: 60 (2Q00 AVWG Off-Cycle Meeting on May 24–25, 2000)        AV/C Printer Subunit Specification Version 1.0 Draft 0.7: 5 (1Q00 TA QM AV-WG on Jan. 18, 2000)        AV/C Printer Subunit Specification Version 1.0 Draft 0.5: 145 (3Q99 TA QM AVWG Meeting on Jul. 28–30, 1999)        